render every conversation turn through one card primitive

The Claude pane's conversation view hand-rolled a separate card layout
per message kind (user/assistant/thinking/tool-use/tool-result), so any
shared chrome had to be added five times. ConversationCard is one
template with three variants (stripe/bordered/bare) that wires the
chrome once: a copy button revealed on hover (yielding the turn's raw
text), an always-visible collapse/expand caret for collapsible turns,
and an extensible MessageAction list. It's decoupled from
ConversationItem — the view maps each item to (variant, accent, label,
body, copyText, actions) — so the typed event cards coming with the
stream-json work reuse the same chrome with a different body.

T-173.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/builtin/claude/conversation_card_test.dart

@@ -0,0 +1,109 @@
+import 'package:clide/builtin/claude/src/conversation_card.dart';
+import 'package:flutter/gestures.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import '../../helpers/kernel_fixture.dart';
+import '../../helpers/widget_harness.dart';
+
+void main() {
+  late KernelFixture f;
+  setUp(() async {
+    f = await KernelFixture.create();
+    // Let Clipboard.setData complete instead of throwing on the unmocked
+    // platform channel, so ClideClipboard.writePlain reaches its history push.
+    TestWidgetsFlutterBinding.ensureInitialized().defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (_) async => null);
+  });
+  tearDown(() {
+    TestWidgetsFlutterBinding.ensureInitialized().defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
+    f.dispose();
+  });
+
+  // Move a synthetic mouse over the card so the hover-revealed actions appear.
+  Future<void> hoverCard(WidgetTester tester) async {
+    final g = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    await g.addPointer(location: Offset.zero);
+    addTearDown(() => g.removePointer());
+    await g.moveTo(tester.getCenter(find.byType(ConversationCard)));
+    await tester.pump();
+  }
+
+  testWidgets('copy button (on hover) writes the copyText to the clipboard', (tester) async {
+    await tester.pumpWidget(harness(
+      f,
+      const ConversationCard(
+        accent: Color(0xFFFFFFFF),
+        label: 'you',
+        copyText: 'the raw message',
+        body: Text('the raw message', textDirection: TextDirection.ltr),
+      ),
+    ));
+    await tester.pump();
+    expect(find.text('copy'), findsNothing); // hidden until hover
+
+    await hoverCard(tester);
+    expect(find.text('copy'), findsOneWidget);
+
+    await tester.tap(find.text('copy'));
+    // writePlain awaits the clipboard channel; let the real async settle.
+    await tester.runAsync(() => Future<void>.delayed(const Duration(milliseconds: 20)));
+    expect(f.services.clipboard.readAs<String>(), 'the raw message');
+  });
+
+  testWidgets('collapsible card hides its body until expanded', (tester) async {
+    await tester.pumpWidget(harness(
+      f,
+      const ConversationCard(
+        variant: ConversationCardVariant.bordered,
+        accent: Color(0xFFFFFFFF),
+        label: 'result',
+        collapsible: true,
+        collapsedByDefault: true,
+        body: Text('tool output here', textDirection: TextDirection.ltr),
+      ),
+    ));
+    await tester.pump();
+    expect(find.text('tool output here'), findsNothing); // collapsed
+
+    await tester.tap(find.bySemanticsLabel('Expand'));
+    await tester.pump();
+    expect(find.text('tool output here'), findsOneWidget); // expanded
+    expect(find.bySemanticsLabel('Collapse'), findsOneWidget);
+  });
+
+  testWidgets('a non-collapsible card always shows its body and no caret', (tester) async {
+    await tester.pumpWidget(harness(
+      f,
+      const ConversationCard(
+        accent: Color(0xFFFFFFFF),
+        label: 'claude',
+        body: Text('always visible', textDirection: TextDirection.ltr),
+      ),
+    ));
+    await tester.pump();
+    expect(find.text('always visible'), findsOneWidget);
+    expect(find.bySemanticsLabel('Expand'), findsNothing);
+    expect(find.bySemanticsLabel('Collapse'), findsNothing);
+  });
+
+  testWidgets('custom actions appear on hover and invoke', (tester) async {
+    var forked = false;
+    await tester.pumpWidget(harness(
+      f,
+      ConversationCard(
+        accent: const Color(0xFFFFFFFF),
+        label: 'claude',
+        body: const Text('body', textDirection: TextDirection.ltr),
+        actions: [MessageAction(label: 'fork', onInvoke: () => forked = true)],
+      ),
+    ));
+    await tester.pump();
+    expect(find.text('fork'), findsNothing);
+
+    await hoverCard(tester);
+    await tester.tap(find.text('fork'));
+    await tester.pump();
+    expect(forked, isTrue);
+  });
+}